Until recently riding fixed gear on the road was the off-season activity of serious club cyclists who were looking to get quality base miles in with a minimum time expenditure in bad weather, develop a supple efficient pedaling technique and prevent wear & tear on expensive components that were removed from the road bike on the annual winter conversion to FG. That's how I started riding FG > 40 years ago and have kept at it ever since.

Riding FG on the road is not for everyone, it takes a rigorous dedication to technique and the proper kit. I'd not recommend it as a weight loss program per se or to anyone w/o a certain amount of experience riding conventional road bikes at pace. Old hand me downs may be OK to poodle about the neighborhood but FG road riding demands precision, ruggedness, a good front brake and a track hub. A good tool costs what it costs (good recommendations from previous posters) and a dedication to it's use is required of it's user.

-Bandera